The Programmer Whose Code Underpins The Internet

Sharla Boehm earned a school grade from nan University of California, Los Angeles, earlier she channeled her talent for mathematics into machine programming. While moving astatine nan RAND Corporation, she built a groundbreaking simulation, primitively conceived to fortify subject communications during nan acold war. The simulation—and her work—would yet laic nan instauration for nan modern Internet. 

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Archival: What if a informing siren sounds? What should you do? Don’t hesitate. Find cover.

Katie Hafner: In nan early 1960s, nan United States and nan Soviet Union were successful a treacherous standoff. Each broadside was connected precocious alert, pinch a increasing stockpile of atomic weapons — fresh to motorboat astatine nan first motion of an attack.

U.S. authorities weren’t conscionable worried astir really to upwind an first attack. They worried astir really they would equine a counterattack if a explosive knocked retired communications.

After all, these vulnerable systems were highly susceptible to atomic attack. If 1 explosive deed conscionable right, each subject communications could spell down, leaving nan full state fundamentally defenseless.

So, nan U.S. subject put scientists to work. Their charge: to invent a communications web that could past an attack. And connected nan squad was 1 intelligence who created an ingenious machine simulation — utilizing 1960s-era computers.

Doug Rosenberg: As a portion of programming, it’s conscionable unthinkable that she could do what she did. I mean, beyond comprehension.

Katie Hafner: And then, she would each but vanish into history arsenic soon arsenic her activity was done.

Katie Hafner: This is Lost Women of Science. I’m Katie Hafner. And coming we person nan communicative of Sharla Perrine Boehm, a superb machine programmer — and truthful overmuch more.

The simulation she created successful nan early 1960s wouldn’t conscionable beryllium offered up arsenic a measurement to safeguard U.S. communications successful nan arena of a atomic attack… It was truthful ingenious that later, agelong aft she near nan field, her activity would thief bring astir 1 of nan astir world-changing inventions ever: nan internet.

But earlier we start, a mea culpa from me. In 1996, my book, Where Wizards Stay Up Late: The Origins Of The Internet, was published. It's a definitive history of nan Arpanet, nan web that would yet germinate into nan internet. And I ne'er erstwhile mentioned Sharla — ne'er moreover came crossed her name. Actually, that can’t beryllium true. She co-authored a awesome paper, a insubstantial I must person seen, and yet I ne'er thought to ask, “Who is that?” It was ever nan celebrated man, her workfellow Paul Baran, that I focused on.

And so, I want to dress up for that today. And since I’m intelligibly not nan master erstwhile it comes to Sharla Perrine Boehm, I’ve brought successful our shaper Samia Bouzid to show america Sharla’s story.

Samia Bouzid: On nan nighttime of November 24, 1961, it seemed for illustration nan nation’s worst nightmare had travel to pass. The ballistic rocket early informing systems crossed nan U.S. went dormant each astatine once. At a guidelines successful Omaha, officers connected overnight work tried to telephone communications office successful Colorado Springs — but nan telephone lines were dormant too. That could mean 1 of 2 things: Either location had been immoderate inexplicably immense communications failure, aliases nan U.S. was nether attack.

The officers scrambled to aftermath up General Thomas Power, nan commandant successful main of nan Strategic Air Command, who instantly ordered atomic forces connected afloat alert. In nan dark, bomber crews guided their planes onto runways. The U.S. was fresh to strike.

But minutes later, nan Strategic Air Command yet made interaction pinch communications headquarters, by sending radar messages done a bomber that was already successful nan air. And office reported that location was nary attack. It was conscionable a regular, quiet night.

So what happened? It turned retired that a azygous centrifugal astatine a relay position retired successful Colorado overheated and caused nan full strategy outage. It conscionable happened to beryllium nan 1 relay position that each communications passed through.

So present was nan United States, 1 bid distant from an accidental atomic war… each because of immoderate janky telephone circuits. Clearly, thing had to beryllium done.

Paul Baran: This was nan tallness of nan Cold War.

Samia Bouzid: This is nan machine intelligence Paul Baran, speaking successful an oral history recorded by nan Charles Babbage Institute successful 1990.

Paul Baran: And it was a very vulnerable business because there's nary communications that tin past an attack.

Samia Bouzid: At nan clip of that astir fateful outage, he was moving astatine nan RAND Corporation, a salient investigation institute successful Santa Monica, California. Baran and others astatine RAND were moving connected nationalist information issues, including what to do astir its disastrously vulnerable communications system.

The problem boiled down to this: backmost successful nan early 1960s, subject communications mostly happened complete telephone lines and shortwave radio. The circuits that transmitted these communications were centralized. That meant each connection sewage routed done astatine astir 5 nodes, aliases connecting points. If those nodes took a hit, location was nary different path. The full web went down.

And truthful Baran became convinced that nan solution was to create a caller shape of communication. Not pinch phones aliases radio. One that sent messages done computers. And he was already envisioning a web that could past a catastrophic mishap aliases attack.

[Paul Baran speaking successful background]

Basically, group up a web without immoderate cardinal node. Each node is conscionable connected to its neighbors. And then, make judge it's connected to capable neighbors that moreover if immoderate get knocked out, nan web arsenic a full will still survive.

Unfortunately, trading his colleagues connected nan thought wasn't truthful simple. They were mostly experts successful old-school analog communications, not integer computers. And they weren’t particularly willing successful proceeding from nan rogue machine intelligence who had wandered into their turf.

Paul Baran: They'd get a small huffy astir it because, uh, “What nan hellhole is this feline successful machine subject talking astir communications?” People who had a inheritance successful analog connection did not understand integer processing. So, immoderate of nan things 1 would opportunity would sound for illustration utter nonsense.

And Baran couldn’t stamp retired their doubts. Every clip he put 1 interest to rest, personification would raise another.

And his colleagues astatine RAND were conscionable 1 problem. Some of his biggest detractors were besides immoderate of nan astir important group he had to convince: nan managers of AT&T.

AT&T controlled everything to do pinch agelong region communication, and truthful Baran really wanted to get them connected board.

Paul Baran: The full thought astatine nan clip was that we had hoped that AT&T would do this pinch nan Air Force, origin AT&T had nan monopoly.

Samia Bouzid: But erstwhile Paul Baran sounded his thought to nan company, nan consequence was a operation of skepticism and condescension. He ne'er forgot really a room of AT&T engineers reacted erstwhile he tried to picture really his thought would work.

Paul Baran: “Wait a minute, son. You mean you unfastened nan move present earlier nan postulation has near nan different extremity of nan country?” I said, “Yeah.” And they look astatine each other, shingle their heads and say, “Son, this is really a telephone works,” and it sewage beautiful patronizing.

Samia Bouzid: No matter what he said, it conscionable wasn’t capable to triumph complete his colleagues, fto unsocial nan AT&T guys.

They conscionable struggled to fathom that a integer web could reliably get a connection from A to B without relying connected immoderate cardinal nodes.

So what Paul Baran needed was immoderate measurement — aliases personification — to beryllium his thought could work. And that personification turned retired to beryllium a young mathematics coach who worked crossed nan thoroughfare astatine Santa Monica High School. In nan precocious 1950s and early 1960s, she spent summers and sabbaticals moonlighting astatine RAND, penning code. Her sanction was Sharla Perrine.

Sharla would person been nan overseas 1 retired backmost then, nan uncommon female among a oversea of men.

Doug Rosenberg: I mean, women were secretaries backmost then. There were not women successful engineering jobs successful 19, nan early 1960s. It was a bunch of guys successful unit cuts.

Samia Bouzid: This is Doug Rosenberg, a systems engineer.

Doug Rosenberg: There were not women successful engineering jobs successful nan early 1960s. It was a bunch of guys successful unit cuts.

Samia Bouzid: Doug was a adjacent friend of Sharla’s husband, Barry Boehm. He says Sharla could clasp her own. Born successful Seattle, she had grown up successful Santa Monica during nan Depression. Her mother, who had immigrated to nan U.S. from Sweden, raised Sharla by herself — her matrimony ended astir nan clip Sharla’s older sister died successful 1932. Sharla was 2 astatine nan time. So, successful nan Perrine household, location were nary gender roles. If thing broke, location was nary man astir to hole it and nary money to prosecute someone. So, Sharla’s mother figured retired really to do things herself.

Tenley Burke: Her mother was a carpenter, truthful that she could hole things and create things and not person to bargain them. Anything that needed fixing they did themselves.

Samia Bouzid: This is Sharla’s girl Tenley, and she says Sharla was nan aforesaid way.

Tenley Burke: She was conscionable no-nonsense, let’s do it ourselves, you tin do anything. She didn’t for illustration dilly dallying. She sewage down to business, and that’s conscionable who she was. She was superior astir everything she did.

Samia Bouzid: Sharla ever had a knack for math, and aft earning a grade successful school from UCLA, she went connected to thatch math, first astatine a inferior precocious and past astatine a precocious school. But she besides gravitated toward programming.

Tenley Burke: I could spot that RAND was a propulsion for her because it was truthful section and it was afloat of group who were reasoning large thoughts. And she ever said that she liked to talk to men astatine parties because they were talking astir absorbing things, and that’s what she wanted to beryllium doing — she wanted to beryllium successful nan absorbing conversations.

Samia Bouzid: RAND did move retired to beryllium an intriguing workplace. While she was waiting for her information clearance successful 1959, she met personification who would subordinate her successful galore absorbing conversations: a machine intelligence named Barry Boehm. Here’s really he told it to nan Computer History Museum successful 2017.

Barry Boehm: There we were down location successful nan basement and we, we sewage to cognize each different and she's now my wife.

[Background chatter]

Samia Bouzid: In summation to falling successful love, Sharla besides sharpened her programming skills penning elemental machine code. And then, successful nan early 1960s, came her large assignment.

Paul Baran needed personification to beryllium that his large thought — nan 1 that could prevention nan state from its massively unreliable communications systems successful nan arena of an onslaught — could really work.

[AD BREAK]

Doug Rosenberg: The measurement you fig retired if it's gonna activity aliases not is you simulate it.

Samia Bouzid: Doug Rosenberg again. And simulating Paul Baran’s thought became Sharla’s job. The basal thought she needed to simulate went thing for illustration this:

Doug Rosenberg: So you first would return a connection and you'd chop it up into small packets…

Samia Bouzid: Imagine cutting up a letter, and past sending each portion successful a abstracted letter cover crossed nan country, from LA to New York. Each letter cover takes a different route. And there’s nary cardinal station agency that each missive has to walk through.

Doug Rosenberg: It could spell from Los Angeles to Kansas City to Chicago to New York, aliases it should spell from Los Angeles to Dallas to Atlanta to New York, right? So you tin way this packet tons of different ways…

Samia Bouzid: This exertion was thing for illustration an old-fashioned telephone line, wherever a connection followed a hard-wired way from A to B — and if thing went down, nan connection was gone.

In fact, nan measurement Sharla built her network, it could find a measurement to get each connection packet through, nary matter what. It was a batch for illustration nan country’s web of station offices. If 1 station agency burned down, message transportation wouldn’t stop. Mail would conscionable get routed done different office. Same went for Sharla’s simulation. It had nodes, but nary cardinal one.

Doug Rosenberg: And past her simulation had immoderate subroutine successful location called “damage.” And, she could tally this “damage” subroutine and say, “Alright, everything's moving smoothly — now let's harm it by knocking retired these 5 nodes,” and past spot really it responded.

Samia Bouzid: Some connection packets would inevitably get lost, but Sharla recovered that if you made a fewer copies of each packet and sent them down different paths, you could guarantee that astatine slightest 1 transcript would make it. And then, erstwhile each nan abstracted packets sewage to nan different side, they would usage serial numbers successful their headers to put themselves backmost successful order. And conscionable for illustration that, you could publication nan original message.

Paul Baran called this method “hot murphy routing,” because each clip a packet arrived astatine a node, that node had to footwear it to nan adjacent 1 arsenic quickly arsenic possible.

And nan instrumentality — really nan brilliant — down this method was that location was nary fixed way for each “hot potato.” The web itself made up nan way successful existent time. So, if 1 node abruptly went down, nan web would conscionable nonstop nan basking murphy a different way. Essentially, nan web would heal itself.

Doug Rosenberg: It healed successful position of, “Oh, good you conscionable took retired those 5 nodes, but I cognize really to respond to that now.”

Samia Bouzid: In Sharla's simulation, each packet changed its way connected nan fly, depending connected nan authorities of nan network. All successful existent time. And nan truth that she pulled this disconnected pinch 1960s machine powerfulness is beautiful mind-blowing.

Doug Rosenberg: If this was 2025, this would beryllium called instrumentality learning because that's really what it was. She was school nan web to study really to respond to nodes dropping out. Machine learning was decidedly nonexistent astatine that point. And yet, if you look astatine this 1964 paper, it's benignant of unquestionably what it is.

Tony Rutkowski: To person this knowing of itself and to accommodate itself is thing that's beautiful profound.

Samia Bouzid: That’s Tony Rutkowski. He’s an technologist and lawyer and history buff who’s spent much than 50 years moving successful accusation communications. He worked connected net argumentation astatine nan Federal Communications Commission successful nan 1980s, and he was really nan 1 who tipped america disconnected to Sharla’s unthinkable work.

Tony Rutkowski: Here you had nan web itself imbued pinch this, this AI! It's nan first spark of, if you will, web AI that was created. That really changed everything.

Samia Bouzid: First and foremost, Sharla’s simulation gave Paul Baran nan impervious he was looking for. Proof that it was imaginable to create a nationwide web that was intelligent and resilient.

Her simulation showed that moreover if half nan web sewage destroyed instantly, nan remaining nodes reorganized themselves and sewage communications going again successful nether a second.

To Paul Baran’s frustration, AT&T ne'er came astir — but according to him, their guidance wasn’t each based connected method doubts.

Paul Baran: It sewage to a constituent erstwhile upon a time, adjacent nan extremity of dealing pinch them, is, they're saying, well, "First it isn't gonna work. And nan second, if it did work, we're not gonna put [them] successful title pinch ourselves." So, it ne'er sewage taken very earnestly by AT&T each during that time.

Samia Bouzid: Nevertheless, some RAND and nan Air Force were wholly connected committee pinch putting basking murphy routing into practice, and they could person gone up and done it — moreover without AT&T’s dollars. They conscionable had to spell done nan Department of Defense to get nan funding.

This is wherever I would emotion to beryllium capable to opportunity that Sharla’s simulation quickly sewage built and we put down nan weapons that were connected precocious alert, and everyone breathed a sigh of relief. But, unluckily that’s not precisely really it went.

The problem was, Paul Baran didn’t person overmuch assurance successful nan Defense Communications Agency, which would beryllium getting nan backing from nan DoD. He conscionable didn’t deliberation they could really instrumentality this caller exertion correctly. And he was acrophobic that if they botched it, it would beryllium really difficult to ever get nan task disconnected nan crushed again.

Paul Baran: We had zero method competence. We had immoderate discussions and mutually concluded that each they would do is screw it up. So I recovered myself successful nan position of recommending they not proceed. And that's what happened.

Samia Bouzid: The DoD did not springiness nan agency nan costs to build nan distributed network. And Sharla’s superb activity sewage tucked away… until it reemerged successful a wholly caller shape respective years later.

In October 1969, a connection popped up connected a machine surface astatine Stanford University successful Northern California. Well, portion of a message. It was nan letters “l-o,” sent from different machine hundreds of miles distant astatine UCLA. The remainder of what should person been nan connection “login” ne'er made it.

But, arsenic anticlimactic arsenic that whitethorn sound, this incomplete connection was nan first connection sent complete nan ARPANET, an early machine web that nan DoD’s Advanced Research Projects Agency was building — not to protect nan state successful lawsuit of an attack, but to stock computing resources crossed institutions.

Within a fewer years of that first botched message, dozens of universities and government-run investigation organizations had connected to nan network. And each of nan messages sent crossed this web were happening acknowledgment to 1 cardinal technology: packet-switching.

This is what “hot murphy routing” yet came to beryllium called. Those mini chunks of broken-up messages are nan “packets,” and it’s “switching” because of nan measurement nan routes betwixt nodes alteration successful existent time. So, packet switching.

This exertion — really, Sharla’s exertion — is what made it imaginable for messages to get chopped up, alert crossed a machine web from UCLA to Stanford aliases MIT aliases NASA, and reassemble connected nan different end.

But nan ARPANET was conscionable nan beginning.

Tony Rutkowski: What's referred to arsenic nan net is really different furniture connected apical of nan integer packet network.

Samia Bouzid: Tony Rutkowski again.

Tony Rutkowski: It's conscionable different furniture of an intelligent adaptive web connected apical of different one. You tin really concatenate these things successful different layers.

Samia Bouzid: That’s right. That resilient web that Sharla coded up successful nan 1960s underpins our full modern internet.

In nan 1990s, location were immoderate lively debates astir who had been nan “father” of nan internet. A fewer names were bouncing around. Sharla’s colleague, Paul Baran, was 1 of them, acknowledgment to his activity connected packet switching. Then location was nan British machine intelligence Donald Davies, who was moving connected akin things astir nan aforesaid time. Meanwhile, nan American machine intelligence Leonard Kleinrock based on that that grant of inventing packet switching really belonged to him — and that he was, quote, nan “Inventor of nan Internet Technology.”

But arsenic for Sharla Perrine Boehm, that sanction didn’t travel up.

Maybe because, by nan clip nan ARPANET was taking off, Sharla had near RAND — and nan world of machine programming altogether.

In 1965, 1 twelvemonth aft her insubstantial connected packet switching was published, she had her first daughter. And she near RAND to go a stay-at-home mom. Her husband, Barry, stayed successful nan world of machine science, and he was intimately progressive arsenic nan ARPANET emerged. But, Sharla put that section of her life down her. Here’s her girl Tenley again.

Tenley Burke: What she really wanted to do was person a family, and participate successful that family fully. And I put that down to her puerility and her mother being a azygous mother during nan Depression and not being capable to beryllium home. I deliberation it was a life accomplishment for her to beryllium capable to enactment home.

Samia Bouzid: And Tenley thinks that nan decease of Sharla’s sister each those years agone influenced her determination too.

Tenley Burke: I deliberation location were things that haunted her from her past that she conscionable didn’t want to repeat. She wanted everyone to beryllium safe and sound.

Samia Bouzid: For nan adjacent mates decades, she put each her power into her family and community, particularly nan Girl Scouts. Caroline Batzdorf was friends pinch Sharla’s daughters and she was besides 1 of those Girl Scouts. She knew Sharla really well.

Caroline Batzdorf: She was 1 of nan astir understated women I've ever known. Just softly getting connected pinch it. Not drafting attraction to herself successful immoderate way, conscionable putting different group forward. She was successful nan inheritance pinch her manus astatine our backs. Encouraging america to strive, encouraging our creativity, showing up, being supportive, making judge that we were well-rounded, softly persistent successful each these ways wherever she made a difference.

Samia Bouzid: And Sharla ne'er really talked astir her past life arsenic a machine programmer. Tenley was successful her 20s earlier her mother moreover told her conscionable what she had done astatine RAND.

Tenley Burke: Sharla poured herself into motherhood and organization work and Girl Scouts, and yeah, location was conscionable nary consciousness successful talking about, you know, “One clip I was a programmer astatine RAND and I wrote immoderate code.” It conscionable wasn't thing that she would mention.

Samia Bouzid: Hearing Sharla’s story, it would beryllium easy to lump her successful pinch truthful galore women whose stories we research connected this podcast — women who had to springiness up their activity to raise kids because nine said so, women who had truthful overmuch to offer, but conscionable ne'er sewage nan chance.

But, everyone I talked to who knew Sharla personally insisted that she ne'er saw it that way. She loved mathematics and machine programming, but she moved connected from RAND, moreover arsenic nan activity went connected without her.

Tenley Burke: I deliberation she was proud of it. I deliberation it was astir apt quirky to her that thing she did successful nan early sixties turned into nan internet. I mean, I mean, really bizarre is that?

Samia Bouzid: But she didn’t dwell connected it. She had much to offer.

Tenley Burke: Sharla was truthful galore things. She was intelligent, she was organized, she was strict. She was kind. She cared. She worried. She was present. She wanted to help. She wanted everyone to win and effort their hardest.

Samia Bouzid: Friends who knew Sharla opportunity she should perfectly beryllium celebrated for her technological achievements, but not reduced to them because she did truthful overmuch much pinch her life.

She raised a family, she nurtured her community, and she traveled often — accompanying her husband, Barry, whenever his activity arsenic a machine intelligence took him to absorbing places.

Tenley Burke: They were decidedly 2 peas successful a pod. As they aged, they would beryllium adjacent to each different and autumn dormant pinch their heads, like, tipped towards each other. It was nan cutest thing. They were, they were rather nan team.

Samia Bouzid: In 2012, Sharla had a changeable that near her incapable to speak, though Tenley says she could still perceive group and smile.

By nan clip Sharla Perrine Boehm died successful 2023, astatine nan property of 93, astir two-thirds of nan world’s organization was utilizing nan net that she had unknowingly helped usher successful arsenic a young machine programmer.

But passim her decades arsenic a teacher, mother, and organization leader, she besides touched galore lives overmuch much intimately. She was nan female supporting truthful galore girls, focused not connected her ain legacy, but connected theirs, connected really overmuch they could accomplish, now that nan world was theirs.

Katie Hafner: This section of Lost Women of Science was produced by Samia Bouzid, pinch thief from elder shaper Laura Isensee. Our elder managing shaper is Natalia Sánchez Loayza.

David De Luca was our sound designer and engineer. Lizzie Younan composed each of our music. We had fact-checking thief from Lexi Atiyah.

Thanks to Eowyn Burtner, our programme manager, Amy Scharf, my co-executive producer, and Jeff DelViscio astatine our publishing partner, Scientific American.

Lost Women of Science is funded successful portion by nan Alfred P. Sloan Foundation, nan Anne Wojcicki Foundation, and galore generous individual donors. We're distributed by PRX.

For show notes and an section transcript, caput to lostwomenofscience.org, wherever you tin besides support our activity by hitting nan donate button.

I’m your host, Katie Hafner. Thanks for listening!

Host
Katie Hafner

Producer
Samia Bouzid 

Senior Producer
Laura Isensee

Guests

Doug Rosenberg is a systems technologist and was a friend of Sharla’s husband, Barry Boehm. He is nan laminitis and CEO of Parallel Agile, Inc. and teaches astatine nan Caltech Center for Technology and Management Education.

Paul Baran was a machine technologist who worked astatine RAND successful Santa Monica, California, wherever he helped create nan underpinnings of nan Arpanet, nan government-sponsored precursor to nan modern internet. He died successful 2011. He is featured done excerpts from his oral history recorded by nan Charles Babbage Institute.

Tenley Burke is 1 of Sharla’s 2 daughters. She has worked astatine nan University of Idaho and is connected nan committee of Boehm Center for Systems and Software Engineering. An avid traveler and gardner, she is besides nan proud mom of 2 boys.

Tony Rutkowski is an engineer, lawyer and history buff. His profession spans telecommunications, mobile, internet, outer and broadcasting fields successful nan U.S. and Europe. He worked connected net argumentation astatine nan Federal Communications Commission successful nan 1980s.

Caroline Batzdorf was friends pinch Sharla’s daughters and progressive successful nan Girl Scouts that Sharla helped support.

Further Reading:

Where Wizards Stay Up Late: The Origins of nan Internet, Katie Hafner and Matthew Lyon, Simon & Schuster, 1996 

Recoding Gender, Women’s Changing Participation successful Computing, Janet Abbate. MIT Press, 2012

Season 2: A Grasshopper successful Tall Grass. Lost Women of Science, 2022